This invention relates to a control handle and system for controlling the operation of a materials handling truck, particularly by an operator walking along side the truck.
A typical rider pallet truck comprises a power unit, a steering control unit and load carrying forks. The power unit contains a steerable wheel, an electric traction motor and an electric storage battery. The power unit also includes a platform onto which the operator may step and ride while controlling the truck. The steering control unit includes a handle which the operator uses to control steering and it also contains operator controls such as twist grips for controlling the direction (forward and reverse) and speed of the truck, a coast control, braking control, controls for raising and lowering the forks, a horn switch and a reversing switch. The load carrying forks extend rearwardly from the power unit and usually have small wheels near the rearmost position to aid in supporting the load.
When the truck is moved in one increment over long distances, four or more bays (36 feet or more), the operator will usually step up onto the truck and ride. In modern warehouses, an order picking procedure is usually organized in such a way that the operator follows a unidirectional serpentine route through the storage area, picking up stock in a predetermined sequence in order to maximize productivity. Since it is inefficient for the operator to ride the truck when moving only short distances, the operator will usually place the truck in its coast mode and walk along side, picking up the materials from the storage area and placing those materials on a pallet on the forks.
Control of the truck's steering while either riding or walking is done by using a conventional steering control handle. Some trucks have been provided with a side control switch placed for use by the operator to control forward motion of the truck.
In a typical operation, the operator may use the side switch to accelerate the truck to walking speed. When approaching a stopping point, the operator will release the switch and allow the truck to coast while the operator moves to an adjacent rack or shelf to pick up an item and place it on a pallet on the forks. The operator plans the coast of the truck so that the pallet on the forks will stop near the operator's position about the same time the operator is ready to place the item on the pallet. After loading the truck, the operator then again operates the side switch and moves the truck toward the next pick up position.
The rate of acceleration and speed of the truck may be controlled by jogging the side switch on and off. The coast distance may be controlled by limiting the truck's travel speed prior to releasing the side switch, and of course the time when the side switch is actually released. Generally, the brakes are not needed during this mode of operation although the truck's brakes are of course available for any emergency. It is clear that inadvertent operation of the side switch must be avoided as well as in providing a side switch that is easily operated by the operator.